This summary shows which detail codes are associated with which commands.
Command Reject (Bit 0).
8004 See Dial.
8005 See Enable and Dial.
8006 See Listen.
800B See Listen.
Intervention Required (Bit 1).
4020 See Listen.
4024 See Dial.
402A See Enable and Dial.
402C See Enable and Dial.
4033 See Enable and Dial.
4034 See Listen.
4035 See Enable, Disable, Dial and Listen.
Data Check (Bit 4).
0894 See Listen.
0897 See Listen.
0898 See Dial.
Lost Data (Bit 6) 02CO See Listen.
02C1 See Listen.
02C7 See Listen.
Timeout (Bit 7)
01E7 See Dial and Listen.
01EC See Disable.
01 F 4 See Listen.
Sense Codes per Command
Enable
The following is a break-down of sense codes as they can appear for each com-mand.
Sense
8005
402A
402C
Description
The addressed line is not in disabled state when the Dial or Enable command is initiated.
DCE is not 'ready' (state 1) at Dial or Enable command initiation or execution. Line is cleared, set to 'DCE controlled not ready' state 14.
Procedure error. Abnormal condition when waiting for 'proceed to select' or 'incoming call':
1. More than expected number of characters received.
2. Character other than 'BEL' or
'+'
received.3. Invalid SDLC sequence received.
Line is cleared, set to 'DTE controlled not ready' state 14.
4033 Connection cleared (,DCE clear') before completion. Line is set to 'DTE controlled not ready' State 14.
4035 Comparator error. Will be set if a difference between input and out-put of any line converter in the interface card is detected. Above indication can erroneously be forced if the cables (internal or external) are not correctly plugged so that the balanced receiver is floating. This could also be the case if the TEST key is pushed on the DCE. Line is cleared, set to 'DTE controlled not ready' state 14.
Dial
Sense
8004 8005
4024
402A
402C
Description
The line is not X.21 switched.
The addressed line is not in disabled state when the Dial or Enable command is initiated.
The loss of the external clock signal (DCE clock) is detected during the execution of a Write Type command. Line is cleared, set to 'DTE controlled not ready' state 14.
DCE is not 'ready' (state 1) at Dial or Enable command initiation or execution. Line is cleared, set to 'DCE controlled not ready' state
14.
Procedure error. Abnormal condition when waiting for 'proceed to select' or 'incoming call';
1. More than expected number of characters received.
2. Character other than 'BEL' or
'+'
received.3. Invalid SDLC sequence received.
Line is cleared, set to 'DTE controlled not ready' state 14.
0898 Format error. An invalid character was detected in the selection sequence. Line is cleared, set to 'DTE controlled not ready' state 14.
4033
01E7
Connection cleared (,DeE clear') before completion. Line is set to 'DTE controlled not ready' State 14.
'Proceed to select' (state 3) .not received following 'call request' (state 2) or 'ready for data' (state 12) not received following 'DCE waiting' (state 6) or 'Call accepted' not properly terminated. Line is cleared, set to 'DTE controlled not ready' state 14.
Listen
Comparator error. Will be set if a.difference between input and out-put of any line converter in the interface card is detected. Above indication can erroneously be forced if the cables (internal or external) are not correctly plugged so that the balanced receiver is floating. This could also be the case if the TEST key is pushed on the DCE. Line is cleared, set to 'DTE controlled not ready' state 14.
The Listen command is not preceded by Enable or Dial.
The Listen command is issued to a line that is already in data phase.
Connection cleared (,DCE clear') before completion. Line is set to 'DTE controlled not ready' State 14.
Non-retry type Call Progress Signal received: 22, 4X, 5X, 7X, 8X or unrecognizable. Line is cleared, set to 'DTE controlled not ready' state 14
Unrecognizable DCE provided information (no
'+'
received)or invalid CPS received. Line is cleared, set to 'DTE controlled not ready' state 14.Format error. The call progress report received was not equal to two characters or did not end with IA5
"+"
delimiter. Line is cleared, set to 'DTE controlled not ready' state 14.'Proceed to select' (state 3) not received following 'call request' (state 2) or 'ready for data' (state 12) not received following 'DCE waiting' (state 6) or 'Call accepted' not properly terminated. Line is cleared, set to 'DTE controlled not ready' state 14.
Retry type Call Progress Signals received: 20, 21, 23 or 61. Line is cleared, set to 'DTE controlled not ready' state 14.
At least one full character has been received and lost because no Lis-ten command was active. The line is disabled. Line is cleared, set to 'DTE controlled not ready' state 14.
The length count is decremented to zero without a trailing flag for read (including Listen) command being received. The command is' terminated immediately. Line is cleared, set to 'DTE controlled not ready'state 14.
A 'halt I/O' instruction is issued while a read-type command (includ-ing Listen) is active. The command is terminated immediately. Line is cleared, set to 'DTE controlled not ready' state 14.
Comparator error. Will be set if a difference between input and out-put of any line converter in the interface card is detected. Above indication can erroneously be forced if the cables (internal or
Disable
Sense
01EC
4035
external) are not correctly plugged so that the balanced receiver is floating. This could also be the case if the TEST key is pushed on the DCE. Line is cleared, set to 'DTE controlled not ready' state 14.
Description
DCE did not signal clear confirmation (DCE ready) within 2 seconds. Line is cleared, set to 'DTE controlled not ready' state 14.
Comparator error. Will be set if a difference between input and out-put of any line converter in the interface card is detected. Above indication can erroneously be forced if the cables (internal or external) are not correctly plugged so that the balanced receiver is floating. This could also be the case if the TEST key is pushed on the DCE. Line is cleared, set to 'DTE controlled not ready' state 14.
X.21 Short Hold Mode
To avoid paying for a line connection even though no useful data traffic goes on, the "short hold mode" is offered on X.21 switched lines. The short hold mode consists of a set of optional parameters that can be specified via the Set Mode command. When specified, the communication adapter monitors the line for actual data traffic as soon as the data transfer phase is established on the DTE/DCE interface. If nothing but non-productive polling goes on (during an Autopoll command), the communications adapter clears the connection after a given time interval and reports this clearing back to the software in form of a soft error (which preserves the session). Short hold mode is put into effect by addi-tional parameters in the Set Mode command.